1. Technical Field
The present invention relates to a liquid discharge control apparatus and a liquid discharge control method.
2. Related Art
An ink jet printer includes a print head which is provided with a plurality of nozzles for discharging ink. In such a print head, clogging in some of the nozzles is likely to take place due to factors such as increasing of ink viscosity, mixing of bubbles and attaching of dust or paper powder. The clogging of the nozzle (discharge abnormality) generates dot omissions (a kind of degradation relating with a quality of image) due to a phenomenon in which the ink to be discharged is actually not discharged on the recording media.
As a related art, an ink jet printer is known in which the dot discharge not performed by defective nozzles among a plurality of nozzles provided in the print head is performed by another nozzle instead (see JP-A-2002-144549).
It is necessary to prevent the degradation of quality of image in which the dot omission described above can be exposed to view.
As described in JP-A-2002-144549, the dot discharge to be performed by a defective nozzle can be performed by another nozzle instead to resultantly remove the dot omission.
In addition, overlap printing is known in which the recording operation is performed using a plurality of nozzles (plural times of passages which the print head performs) for each raster line for forming the image to be recorded. According to the overlap printing, since the ink is discharged through a plurality of nozzles to record one raster line on the recording media, an effect which the ink discharge performed by one nozzle has on the result of the recording (quality of image) may be spread over the entire raster lines. For this reason, compared with a case in which the raster line is recorded through one nozzle (one time of passage of a print head), the overlap printing may provide an improved quality of image for example, an effect in which the positional shift of the dot caused by transport error of the recording media is not explicitly exposed to view. Further, if the entire dot discharge to be performed by the defective nozzle is performed by another nozzle instead, the dot omission does not occur in the overlap printing.
In view of the above consideration, since the degradation of the quality of image due to the dot omission and the degradation of the quality of image due to the excessive use of the same nozzle as that at the time of recording the raster line may be suppressed with good balance, the quality of image can be entirely improved.